I'm not sure if this is exactly what you meant by a backtrace, but here we go.

I was able to follow the instructions when logged in remotely, so yay!

I did the following:

Logged into a gnome session.
Started gdb and attached it to my running Xorg process
continued the thread (cont)
rotated the screen with 'xrandr -o left'
At this point my mouse can move around the screen (still being updated) and I can 'interact' with windows. However, nothing changes on my screen (except for that mouse) and I do not see any of my windows moving for example if I drag them around the screen.
I do a ctrl-c in gdb, then running backtrace full
This is the result: (the SIGINT is my ctrl-c I think)


(gdb) cont
Continuing.

Program received signal SIGINT, Interrupt.
[Switching to Thread 0xb7bdba30 (LWP 5976)]
0xb7f06410 in __kernel_vsyscall ()
(gdb) backtrace full
#0  0xb7f06410 in __kernel_vsyscall ()
No symbol table info available.
#1  0xb7d4984d in select () from /lib/tls/i686/cmov/libc.so.6
No symbol table info available.
#2  0x081b2275 in WaitForSomething (pClientsReady=0xbff15eb0)
    at ../../os/WaitFor.c:236
    i = <value optimized out>
    waittime = {tv_sec = 0, tv_usec = 400000}
    wt = (struct timeval *) 0xbff15e70
    timeout = <value optimized out>
    clientsReadable = {fds_bits = {0 <repeats 32 times>}}
    clientsWritable = {fds_bits = {1, 138314432, -1074700904, 134833857,
    -1074700888, 1, -1074700764, -1210805528, -1074700764, 43, -1074700776,
    136163204, 1, 32, -1074700856, 136039262, 43, -1074700764, 1, 0,
    138314432, 136163204, -1074700824, 136034255, 147094224, -1074700764, 1,
    -1073741823, 1, 136713632, -1074700728, 136013494}}
    curclient = <value optimized out>
    selecterr = 0
    nready = <value optimized out>
    devicesReadable = {fds_bits = {140797068, 138314432, -1074700936,
    134819325, 138314432, 32, 140797068, 0, 0, 0, 138314432, 0, 0, 0, 0, 0,
    138277848, 103, 136713632, 136163204, 136694464, 136427336, -1074700936,
    134814362, 136340232, 0, -1074700896, 0, 0, 0, -16121856, 136163204}}
    now = 12092217
    someReady = 0
#3  0x0808d69d in Dispatch () at ../../dix/dispatch.c:425
    result = <value optimized out>
    client = (ClientPtr) 0x83df3d8
    nready = -1
    start_tick = 58640
#4  0x0807471b in main (argc=10, argv=0xbff163e4, envp=0x0)
    at ../../dix/main.c:452
    i = 1
    error = 136163204
    xauthfile = <value optimized out>
    alwaysCheckForInput = {0, 1}
(gdb)


I hope this helps. Interestingly, I tested with an external monitor (17 inch, 1280x1024) and had the exact same thing happen. So I feel that this has to somehow be related to how the driver handles composite mode. (or the card itself, but that seems more unlikely)

Andrew Stromme

On Sat, Apr 19, 2008 at 11:56 PM, Andrew Stromme <andrew.stromme@gmail.com> wrote:
One more thing before I go to bed. The exact same thing happens using kwin (from kde 4.0.3) when 3d effects (so also the compositing functions) are enabled.


On Sat, Apr 19, 2008 at 11:53 PM, Andrew Stromme <andrew.stromme@gmail.com> wrote:
Interesting. If I kill compiz while rotated, my screen will come back (it's a bit glitchy, but when I start metacity the entire screen refreshes and it's all good). If I try and start compiz, I get the same problem. I don't see any weird notifications from compiz while it is starting in this method.

Let me try with kwin and its compositor.

On Sat, Apr 19, 2008 at 11:46 PM, Andrew Stromme <andrew.stromme@gmail.com> wrote:
Sorry, the debs don't seem to change anything. I looked at the linked page, but I'm having trouble getting a good backtrace. Every time I try to attach with gdb (even from a VT in ctrl-alt-f1) my Xorg window freezes. and I must reboot using the sysrq combinations. I can try with a network attached pc later, but until tomorrow I can't be of much more help. Any idea about the hard lockups?

Andrew


On Fri, Apr 18, 2008 at 9:09 PM, Bryce Harrington <bryce@bryceharrington.org> wrote:
Another thing to try, is if after rotating and locking up, if you can
ssh in and kill compiz processes, does it come back properly?  If so, it
may be a compiz issue rather than X.

--
XRandR Rotation with -intel doesn't work with compiz [x3100]
https://bugs.launchpad.net/bugs/218000
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